Turntable/Subwoofer Ground loop


I have a Rel B1 that is hooked up to Cary MB500 monoblocks via the high level connections.

I am starting to get a ground loop hum from the sub when I play a record. Only when the needle hits the record does it start. I have re-checked all connections, what could it be?

All the ground wires are connected what I think is correctly, but the high level connection from the amps to the sub has the wires stretched quit a bit to reach the amps and the ground.

Should I ground the Sub connection to somthing different, like the rack???
macdadtexas
I had this same issue with my Rel Stadium III, after I changed from at stereo amp to mono blocks. Take the ground wire and connect it to the grounding terminal on your preamp. I also hear that Rel makes a cable for it with 2 ground wires but I have never seen it.
Is the hum the typical 60Hz hum? If it is 60 Hz then it is a ground loop issue. Otherwise, you might try improving the mechanical isolation of your turntable. Low frequency feedback from the sub could be exciting your turntable. Another quick check- invert the phase on the sub and see if the hum stops. That might also indicate a mechanical feedback issue.
Tonywinsc,

I think you may be right. I isolated the phono cable and most of the hum went away, I need to try inverting the phase of the turntable. Good advice, thanks.